Generate Thumbnail From Live URL Of Microsoft Office And PDF file in ASP.NET MVCDec 13, 2017. Recently, I got a chance to create thumbnail images from the live URL. The URLs were not of images but of some DOCX file, some XLSX file, or PDF file. We don’t have any custom library which can directly generate the thumbnail from a live URL. So, here, we will learn how we can customize our code to generate the thumbnail in .NET.